Circuit breaker with thermal and magnetic trip means



Jan. 3, 1967 A. R. CELLERlNl 3,296,554

' CIRCUIT BREAKER WITH THERMAL AND MAGNETIC TRIP MEANS Filed March 9, 1965 4 She'cs-Sheet 1 WITNESSES INVENTOR $7M Albert R. Cellerim pmflw (0.6M

ATTORNEY Jan. 3, 1967 A. R. CELLERINI 3,296,564

CIRCUIT BREAKER WITH THERMAL AND MAGNETIC TRIP MEANS Filed March 9, 1965 4 SheetsSheet 2 Jan. 3, 1967 A. R. CELLERINI I CIRCUIT BREAKER WITH THERMAL AND MAGNETIC TRIP MEANS 4 Sheets-Sheet Filed March 9', 1965 FIG-3.

Jan. 3, 1967 A. R. CELLERINI 3,296,564

CIRCUIT BREAKER WITH THERMAL AND MAGNETIC I MEANS Filed March 9, 1965 4 Sheets-Sheet 4 FIG.9.

United States PatentO 3,296,564 CIRCUIT BREAKER WITH THERMAL AND MAGNETIC TRIP MEANS Albert R. Cellerini, Beaver, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Mar. 9, 1965, Ser. No. 438,271 4 Claims. (Cl. 335-35) This invention relates generally to circuit breakers and more particularly to circuit breakers of the type comprising thermal and magnetic trip means.

An object of this invention is to provide a circuit breaker with an improved thermal and magnetic trip device.

Another object of this invention is to provide a moldedcase type circuit breaker with an improved compactly constructed trip device comprising thermal and magnetic trip means.

For certain applications it is desirable to provide a circuit breaker that can carry 100% of the rated current continuously without tripping; that will trip within two hours when 125% of the rated current is passed therethrough; that will trip within fourteen minutes when 200% of the rated current is passed therethrough; and that will trip instantaneously when a severe overload such as ten times the normal rated current is passed therethrough. Accordingly, another object of this invention is to provide an improved circuit breaker with a compact trip device having the above-set-forth desirable tripping characteristics.

A further object of this invention is to provide an improved circuit breaker comprising a compact thermal and magnetic trip device wherein an induced current is utilized in order to effect heating of the bimetallic member.

A more particular object of this invention is to provide an improved relatively high rated molded-case type circuit breaker having a compact trip device comprising an induction type thermal trip means disposed adjacent an electromagnetic trip device, with the construction and arrangement of parts being such as to provide certain desirable tripping characteristics within certain space limitations.

The invention both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description when read in conjunction with the accompanying drawings.

In said drawings:

FIGURE 1 is a side sectional view illustrating the internal compartment of a three-pole circuit breaker, with certain parts being broken away and with certain parts being shown in elevation;

FIG. 2 is a top elevational view of the removable threepole trip device seen in FIG. 1;

FIG. 3 is a sectional view taken generally along the line IIIIII of FIG. 2;

FIG. 4 is a sectional view taken generally along the line IV-IV of FIG. 2;

FIGS. 5 and 6 are front and end partial views respectively, with parts broken away, of one of the electromagnetic trips seen in FIGS. 3 and 4;

FIGS. 7 and 8 are front and end partial views respectively, with parts broken away, illustrating one of the thermal trips seen in FIGS. 3 and 4; and

FIG. 9 is a front elevational view, with parts broken away, illustrating one of the thermal and magnetic trips of FIGS. 3 and 4, with the magnetic armature being shown in the closed or actuated position.

Referring to the drawings, there is shown in FIG. 1 a circuit breaker 3 comprising an insulating housing 5 and a circuit-breaker mechanism 7 supported within the housing. The housing 5 comprises a base 9 and a cooperating cover 11 both of molded insulating material. The circuit breaker is of the type known in the art as a molded-case or insulating-housing type circuit breaker. The circuit breaker is of the type specifically described in the copending patent application of Albert R. Cellerini et 211., Serial No. 305,792, filed August 30, 1963, and assigned to the assignee of the instant application.

The circuit-breaker mechanism 7 comprises an operating mechanism 13 and a trip device or trip unit 15. The circuit breaker 3 is a three-pole circuit breaker comprising three compartments disposed in a side-by-side relationship within the insulating housing 5. The center compartment or pole unit is separated from each of the two outer pole units by a separate insulating barrier 17, 19 molded integral with the cover 11 and base 9 respectively. The operating mechanism 13 is a single operating mechanism disposed in the center pole unit for simultaneously operating the contacts of all three of the pole units.

Each pole unit comprises a stationary contact 21 that is fixedly secured to a rigid main conductor 23 that is secured to the base 9 by means of bolts 25. In each pole unit a movable contact 27 is welded or brazed to a contact arm 29 that is pivotally mounted on a switch arm 31 by means of a pivot pin 33. Each of the switch arms 31 is pivotally supported at one end thereof on a separate support bracket 34 by means of a separate pivot pin 35. The switch arms 31 for all three of the pole units are connected to move in unison by means of a common tie bar 37 that is rigidly connected to all three of the switch arms. Each of the contact arms 29 is biased about the associated pivot 33 by means of a spring 39 to provide contact pressure in the closed position.

The switch arms 31 are operated to the open and closed positions by means of the operating mechanism 13. The operating mechanism 13 comprises a toggle link 41 that is pivotally connected to an extension 43 of the centerpole switch arm 31 by means of a pivot pin 45. The toggle link 41 is pivotally connected to another toggle link 47 by means ofa knee pivot pin 49. The upper end of the toggle link 47 is pivotally connected to a cradle or releasable member 51 by means of a pivot pin 53. The member 51 is pivotally supported at one end thereof on a supporting bracket 34 by means of a pivot pin 57. The other end 59 of the releasable member 51 is held in a latched position by means of a latch member 61. The operating mechanism 13 also comprises a generally U-shaped operating lever 63 that is pivotally supported on the bracket 34 by means of pivot pins 65 that engage the inner ends of the legs of the operating lever 63. An insulating shield 67, for substantially closing and opening 69 in the cover 11, is secured to the upper end of the operating lever 63. The shield 67 has an integral insulating =handle portion 71 extending out through the opening 69 to permit manual operation of the breaker. Two overcenter springs 75 (only one being shown in FIG. 1) are connected under tension between the knee pin 49 of the toggle 41, 47 and the upper end of the operating lever 63. Pin means 77 are secured to the upper end'of the lever 63 in order to support the upper ends of the springs 75.

In each pole unit, an arc-extinguishing unit 81 is provided to extinguish the are drawn between the associated contacts 21, 27. Each arc-extinguishing unit 81 comprises an insulating housing 83 and a plurality of magnetic steel plates 85 supported within the housing 83. The movable contact 27 moves within a generally V- shaped opening in the stacked plates 85, and the are drawn between the contacts 21, 27 is magnetically moved to the right (FIG. 1) into the plates 85 to be extinguished. Each of the arc-extinguishing units 81 is secured to the associated main conductor 23 by means of four bolts 89 that are threaded into tapped openings in the conductor 23.

For each pole unit, the circuit breaker 3 is provided with two rear-type terminal connectors 91 suitably secured at opposite ends at the back or bottom of the circuit breaker.

Referring to FIG. 1, the circuit through each pole unit of the circuit breaker 3 extends from the right-hand terminal 91 through the conductor 23, the contacts 21, 27, the contact arm 29, flexible conductors 93 that are secured to the contact arm 29 and also to a terminal member 95, the terminal member 95 that is secured to the base 9 by means of a screw 97, a unitary rigid main conductor 99 that is connected to a terminal conductor 95 and that is secured to the base 9 by means of bolts 101 and 103, to the other rear-type terminal connector 91. The bolts 101 and 103 are threaded into tapped inserts 105 in the base 9 to secure the main conductor 99 and removable trip unit 15 to the base 9. Each of the reartype terminal connectors 91 is connected to the associated internal conductor (23 or 99) by means of four bolts 107 in a manner that is specifically described in the aforementioned copending patent application of A. R. Cellerini, Serial No. 305,792.

The circuit breaker 3 is manually operated to the open position by movement of the handle 71 in a counterclockwise (FIG. 1) direction to the off position. During this movement, the line of action of the overcenter spring means 75 is moved to the left to an overcenter position to eifect a collapse of the toggle 41, 47 to pivot the switch arm 31 for the center pole in a counterclockwise direction about the associated pivot 35 to an open position. This movement, because of the connection of all of the switch arms 31 by means of the common tie bar 37, simultaneously moves all of the three switch arms 31 to the open position.

The circuit breaker is manually closed by reverse movement of the handle 71 from the off to the on position. This movement moves the operating lever 63 to move the line of action of the overcenter spring means 75 to the right to thereby reset the toggle 41, 47 moving all three of the switch arms 31 simultaneously to the closed position.

Referring to FIGS. 1-4, the trip device 15 comprises a molded insulating base 113 and a molded insulating cover 115 cooperable with the base to enclose three thermaland-magnetic trip means which are disposed within three compartments in the trip unit housing 113, 115. The compartments are separated by means of cooperating insulating barriers 117, 119 (FIGS. 3 and 4) molded integral with the insulating base 113 and cover 115, respectively. The trip device 15 includes a trip structure 121 comprising a molded insulating trip bar 123 and three stabilizing bimetal members 125 that are fixedly secured to the trip bar 123, each of the stabilizing bimetal members 125 is disposed in a different one of the three pole unit compartments. The trip bar 123, which passes through suitable openings in the trip-unit housing barriers 117, 119, is common to all three of the pole units. The trip bar 123 is pivotally supported on two spaced bracket arms 127 (FIG. 4) that extend out of the base 113. The bracket arms 127 are supported on a suitable supporting bracket 129. Pivot pins 130 pivotally support the trip bar 123 on the bracket arms 127. In addition to the common trip structure 121, the trip unit 15 comprises three thermal-and-magnetic trips means 135 (one for each pole unit) which are disposed generally below (FIGS. 3 and 4) the trip structure 121.

Each of the thermal-and-magnetic trip means 135 comprises an electromagnetic trip means 137 (FIGS. and 6) and a thermal trip means 139 (FIGS. 7 and 8). The electromagnetic trip means 137 (FIGS. 5 and 6) comprises a generally U-shaped part 141 of magnetically permeable material such as soft iron and a clapper type armature 143 which is also of a magnetically permeable material, such as soft iron. As can be seen in FIG. 6, the Ushaped part 141 and armature 143 are both laminated to reduce eddy currents. As can be seen in FIG. 5, there is a generally V-shaped notch 145 formed at the upper end of one of the legs of the U-shaped part 141. The armature 143 comprises a main body part 147 and a support part 149. The support part 149 comprises a spring support 151 and a knife-edge type pivot 153. The pivot 153 engages in the notch 145 to pivotally support the armature 143 on the one leg of the U-shaped part 141. A spring member 155 is supported at one end on the spring support 151 of the armature 143 and at the other end on a stationary support 157 to bias the armature 143 in a counterclockwise (FIG. 5) direction to the open position seen in FIG. 5 wherein a generally flat end part 159 of the armature 143 is spaced from a generally fiat pole face 161 on the other leg of the U-shaped part 141.

The air gap between the armature part 159 and the pole face 161 is adjusted by means of an adjusting mechanism 163 which is of the type specifically described in the patent to G. F. Thomas et al., Patent No. 3,073,925, issued January 15, 1963. For this reason, only a brief description of the adjusting mechanism 163 is given herein.

The adjusting mechanism 163 comprises a cam mem- 7 her 165 having an upper cam surface 167 that is engaged by one end of a lever 169. The lever 169 is pivotally supported intermediate the ends thereof on a supporting bracket 171 by means of a pivot pin 173. The bracket 171 is an L-shaped bracket that is secured to the U-shaped part 141 by means of rivets 175 (FIGS. 3 and 4). The rivets 175 extend through opening-s 176 and the U-shaped part 141 and bracket 171 to secure the U-shaped part 141 and bracket 171 to the trip-unit insulating base 113. A rod 177 extends from the cam 165 to an adjusting knob 179. The knob 179, which passes out through a suitable opening in the trip-unit housing 113, 115, is disposed in a suitable opening in the circuit breaker insulating housing 5 (FIG. 1) whereby the knob 179 is accessible for adjustment from outside of the circuit breaker housing 5. Rotation of the adjusting knob 179 rotates the cam 165 to pivot the lever 169 whereupon an adjusting screw 181 (FIG. 5) on one end of the lever 169 moves against the associated armature 143 to pivot the armature 143 about the pivot 153, 145 thereby varying the magnetic air gap to vary the minimum overload current which will be required to effect an instantaneous magnetic tripping operation.

The circuit breaker is tripped open instantaneously upon the occurrence of a severe overload, of for example ten times the normal rated current, through any of the three pole units of'the circuit breaker. Upon the occurrence of the severe overload or short circuit through one of the conductors 99, the magnetic flux generated in the associated electromagnetic trip 141, 143 is strong enough to attract the armature 143 toward the pole face 161 overcoming the bias of the spring 155, and the armature 143 is moved into engagement with the pole face 161 during which movement the armature 143 pivots about the pivot 153, 145. As the armature 143 moves into engagement with the pole face 161, the rod 185, which is pivotally supported to the armature 143 by means of a pivot pin 186 (FIG. 9), is pulled down whereupon a head portion 189 (FIGS. 3 and 4) on the rod engages a part 191 of the insulating trip bar 123 to pivot the trip bar 123 causing the trip bar to rotate in a counterclockwise (FIG. 4) direction about the pivot pins 130. This movement effects a releasing movement of the latch 61 to disengage the latch 61 from the cradle 51 (FIG. 1). Upon release of the cradle 51, the springs 75 act to rotate the cradle in a clockwise direction about the pivot 57 and to collapse the toggle 41, 47 to thereby pivotally move the three switch arms 31 in a counterclockwise direction to open position.

During the automatic tripping operation the spring means 75 operates to move the operating lever 63 and handle 71 to an intermediate position between the on and 011 positions in a Well-known manner to thereby provide a visual indication that the circuit breaker has been automatically tripped.

Following an automatic tripping operation, it is necessary to reset and relatch the circuit-breaker mechanism before the contacts can be closed. This is accomplished by moving the handle 71 to the full off position. During this movement, a pin 137 that is supported on the operating lever 63 engages a shoulder 139 on the cradle 51 moving the cradle in a counterclockwise direction about the pivot 57. Near the end of this movement, the free or latching end 59 of the cradle 51 earns the latch 61 to the left against the bias of spring means (not shown) and moves below the latching end of the latch 61 whereupon the latch is biased back to the latching position seen in FIG. 1 to relatch the cradle 51 in a wellknown manner. The breaker contacts can then be closed in the previously described manner by movement of the handle 71 to the on position. The electromagnetic tripping operation occurs instantaneously without a time delay upon the occurrence of a predetermined severe overload such, for example, as ten times or more of the normal rated current.

Referring to FIGS. 7 and 8, the thermal trip 139 comprises a generally U-shaped part 201 of magnetically permeable material such as soft iron. The generally U- shaped part 201 comprises a plurality of laminations (FIG. '8). The U.shaped part 201 is supported on the trip unit insulating base 113 (FIG. 4) by means of the same rivets 175 that secure the part 141 of the magnetic trip to the 'base 113. The member 201 is provided with openings 203 (FIG. 7) therein for receiving the rivets 175. A magnetically permeable solid steel bimetal support 205 is supported on the U-shaped part 201 and secured thereto by means of two screws 207 that pass through suitable openings in the support 205. The screws 207 are threaded into tapped openings in the free ends of the legs of the member 201. Nonmagnetic shims 211 are removably disposed (two at each side) between the members 205 and 201. With the provision of the shims 211 an adjustable gap is provided to permit adjustment of the thermal trip 139. A one-turn short circuited conducting member 215 is fixedly supported on the support 205 in a heat-conducting relationship with the support 205. The

member 215 is of a highly conductive material such as copper. A generally L-shaped tripping bimetal member 217 is supported on the turn 215 by means of a screw 219 (FIG. 8) that passes through an opening in the lower short leg 221 of the bimetal 217 and is threaded into a tapped opening in the member 215. The bimetal 217 is fastened to the one-turn short circuited conductor 215 in a heat-conducting relationship with the conductor 215. An adjusting screw 219 is threaded into a tapped opening in the upper end of the vertical leg of the bimetal 217.

Referring to FIG. 7, it will be seen that the laminated U-shaped part 201 and the solid bimetal support bar 205 cooperate to form a one-turn magnetic circuit around the energizing conductor 99. An energizing alternating current through the conductor 99 generates magnetic flux in the magnetic circuit 201, 205 to induce eddy currents in the bimetal support 205 that serve to heat the bimetal support. Hysteresis losses account for additional heating of the bimetal support 205 when the conductor 99 is energized. The eddy current and hysteresis losses are core losses that occur in the form of heat in the bimetal support 205. This heat is conducted directly to the short circuited conductor 215 that is supported on the member 205 in a heat-conducting relationship with the member 205 and then to the bimetal 217 that is supported on the short circuited conductor 215 in a heat-conducting rela tionship with the conductor 215. The conductor 215 also acts as a short circuited secondary of a transformer, and

6 the current in the conductor 99 generates magnetic flux in the circuit 201, 205 to in turn generate eddy currents in the short circuited turn 215 to heat conductor 215, which heat is conducted to the bimetal 217 that is supported on the conductor 215 in a heat-conducting relationship with the conductor 215.

When there is no current running through the circuit breaker 3 the tripping bimetal 217 and stabilizing bimetal 125 are in the positions seen in FIG. 8. The high expansion side of the tripping bimetal 217 is on the left as viewed in FIG. 8 and the high expansion side of the stabilizing bimetal 125 is also on the left as viewed in FIG. 8. When the circuit breaker is in operation and when the circuit is carrying 100% of the rated current, the tripping bimetal 217 is heated through the action of the thermal trip 139 in the same manner as was hereinbefore described and it (the tripping bimetal) is also heated because there is a rise in the ambient temperature within the insulating housing 5 of the circuit breaker. Thus, there is an initial deflection to the right (FIG. 8) of the tripping bimetal 217. It is important that this initial deflection of the tripping bimetal 217 does not trip the circuit breaker since the circuit breaker is rated to carry 100% of the rated current without tripping. Thus, the stabilizing bimetal member 125 is provided. When the circuit breaker is energized to carry 100% of the rated current the stabilizing bimetal 125 deflects to the right (FIG. 8) upon the occurrence of a rise in the ambient temperature within the circuit breaker housing 5 to prevent a tripping operation. When a tripping overload current such, for example, as a current of 125% of the rated current passes through the conductor 99, the tripping bimetal 217 will be heated to deflect sufiieiently to engage the stabilizing bimetal 125 to rotate the trip bar structure 121 to a tripping position to effect a tripping operation of the circuit breaker in the same manner as was hereinbefore described. The circuit breaker thermal trip means 139 is constructed such that the circuit breaker will be tripped Within two hours when 125% of the rated current is passed through the conductor 99. The thermal trip means 139 is constructed such that the circuit breaker will be tripped within 14 minuates when 200% of the rated current is passed through the energizing conductor 99.

The armature 143 (FIGS. 5 and 6) remains in the unattracted position until a severe overload such, for example, as 10 or more times the rated current of the circuit breaker passes through the energizing conductor 99 whereupon the armature 143 will be instantly attracted to the closed position seen in FIG. 7 to effect a tripping operation in the same manner as was hereinbefore described.

Referring to FIG. 9, it will be noted that in the closed position of the armature 143, the generally planar bottom 227 of the main body portion 143 of the armature 147 is higher than the generally planar top part 229 of the bimetal support 205. It is noted in FIG. 9 that the surfaces 159, 161 engage along a plane that is higher than the plane of the generally planar top part 229 of the bimetal support 205. Thus, the bimetal support 205 and main body portion 143 are spaced height-wise in the unit housing 113, and also in the circuit breaker housing 5 (FIG. 1). As can be seen in FIG. 4, the members 143 and 205 are also spaced lengthwise in the circuit breaker housing 5 (FIG. 1). This spacing between the parts 205 and 143 reduces leakage of flux from the bimetal support 205 into the armature main body portion 143 and it (the spacing) reduces the bucking effect between the fluxes generated in the parts 143 and 205. Thus, this reduction in flux leakage and also the reduction in the bucking eflect serve to increase the flux and, therefore, the heating effect in the bimetal support member 205 thereby enabling the applicant to provide an improved tripping device within the space limits of the circuit breaker 3 and also within the space limits of the removable trip-unit housing 113, 115. The trip device has the desirable tripping characteristics of tripping within two hours at 125% of the rated current and tripping within 14 minutes at 200% of the rated current. A trip device of the type herein disclosed and described has been used successfully in a circuit breaker rated to carry 1,600 amps normal current and also in a circuit breaker rated to carry 2,000 amps normal current.

With the bimetal support 205 lower than the armature 147, the bimetal 217 can be elongated (FIG. 4) heightwise within the confinement of the trip-unit housing 113, 115.

In circuit breakers of very high ratings, when the circuit breaker is energized from zero current to 100% of the rated current, the temperature rise of the tripping bimetal, which temperature rise is occasioned by current flow and also by the rise in ambient temperature, is such as to cause the tripping bimetal to deflect. The stabilizing bimetal is provided to deflect along with the tripping bimetal in order to compensate for this movement of the tripping bimetal when the circuit breaker is energized to carry 100% of the rated current. It is also desirable to have the breaker trip within 14 minutes after the breaker is energized to carry 200% of the rated current. In order to provide that the breaker will trip Within 14 minutes after the breaker has been energized to carry 200% of the rated current, the stabilizing bimetal and tripping bimetal are selected such that the stabilizing bimetal does not deflect any substantial amount relative to the tripping bimetal during the change from 100% to 200% of the rated current, whereby the deflecting action of the tripping bimetal is eflective to trip in this range.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes and modifications in the structural details and arrangement of parts may be made without departing from some of these essential features of the invention. It is desired, therefore, that the language of the appended claims be given as reasonably broad an interpretation as the prior art permits.

I claim as my invention:

1. A circuit breaker having a length, a width and a height, said circuit breaker comprising a pair of contacts,

' a trip device comprising a trip structure operable to effect opening of said contacts, said trip device comprising a first magnetically permeable part, an armature, said armature in the closed position cooperating with said first magnetically premeable part to generally encompass a first opening, a second magnetically permeable part supported adjacent said first magnetically permeable part, a magnetically permeable bimetal support member cooperating with said second magnetically permeable part to generally encompass a second opening, a conductor connected in electrical series with said contacts and passing through said first and second openings, said armature comprising a main body portion, said main body portion of said armature being spaced height-wise from said bimetal support member in said circuit breaker, a bimetal 2. A circuit breaker comprising an insulating housing having a length, a width and a height, a circuit-breaker mechanism supported in said insulating housing and comprising a pair of contacts, a trip device comprising a trip member movable toeifect opening of said contacts, said trip device comprising a first magnetically permeable member supported on said bimetal support member in a heat conducting relationship with said bimetal support member, said bimetal support member being adapted to be heated by hysteresis and eddy current losses therein when said conductor is energized, said heat in said bimetal support member being conducted to said bimetal member to heat said bimetal member, said bimetal member when heated a predetermined amount operating said trip structure to eflect opening of said contacts to thereby effect a thermal tripping operation, said thermal tripping opera tion occurring with a time delay upon the occurrence of certain overload current conditions below a predetermined value, upon the occurrence of overload current conditions above said predetermined value said armature being attracted to said first magnetically permeable part whereupon said armature moves to operate said trip structure to efiect opening of said contacts without a time delay.

part, an armature supported to cooperate with said first magnetically permeable part, said armature in the closed position cooperating with said first magnetically permeable part to generally encompass a first opening, a second magnetically permeable part supported adjacent said first magnetically permeable part in the lengthwise direction of said insulating housing, a magnetically permeable bimetal support member cooperating with said second magnetically permeable part to generally encompass a second opening, a conductor connected in electrical series with said contacts and passing lengthwise in said insulating housing through siad first and second openings, a bimetal member supported on said bimetal support member in a heat-conducting relationship with said bimetal support member, said bimetal support member being adapted to be heated by hysteresis and eddy current losses therein when said conductor is energized, said heat in said bimetal support member being conducted to said bimetal member to heat said bimetal member, said bimetal member when heated a predetermined amount bending to operate said trip member to effect opening of said contacts to thereby eifect a thermal tripping operation, said thermal tripping operation occurring with a time delay upon the occurrence of certain overload currents below a predetermined value, said armature being supported to move toward and away from said first magnetically permeable part, in the closed position of said armature said armature being spaced height-wise in said insulating housing relative to said bimetal support member, and upon the occurrence of an overload current above said predetermined value said first magnetically permeable part being energized sufficiently to attract said armature whereupon said armature moves without a time delay to move said trip member to effect opening of said contacts.

3. A circuit breaker comprising an insulating housing having a length, a Width and a height, a circuit-breaker mechanism supported within said housing, said circuitbreaker mechanism comprising a pair of contacts and a trip device, said trip device comprising a trip member movable to effect opening of said contacts, a first magnetically permeable part, an armature cooperable with said first magnetically permeable part, said armature in the closed position cooperating with said first magnetically permeable part to generally encompass a first opening, a second magnetically permeable part supported adjacent said first magnetically permeable part in a direction normal to the direction of the height of said housing, a magnetically permeable bimetal support member cooperating with said second magnetically permeable part to generally encompass a second opening, a conductor connected in electrical series with said contacts and passing through said first and second openings, a short-circuited conductor around said bimetal support member in a heatconducting relationship with said bimetal support member, a bimetal member supported on said short-circuited conductor in a heat-conducting relationship with said short-circuited conductor, said armature comprising a main body part, said main body part being disposed within said circuit breaker between said bimetal support member and said trip member, said main body part being spaced height-wise within said housing relative to both said bi metal support member and said trip member, when said conductor is energized the current through said conductor operating to eflect generation of heat in said bimetal member, said. bimetal member when heated a predetermined amount bending to operatively move said trip memher to effect opening of said contacts to thereby effect a thermal tripping operation, said thermal tripping operation occurring with a time delay upon the occurrence of overload current conditions below a predetermined value, and upon the occurrence of overload current conditions above said predetermined value said first magnetically permeable part being energized to magnetically attract said armature to effect movement of said trip member and opening of said contacts without a time delay.

4. A circuit breaker comprising an insulating housing having a length, a width and a height, a circuitbreaker mechanism supported within said housing, said circuit breaker mechanism comprising a pair of contacts and a trip device, said trip device comprising a trip structure operatively movable to eifect opening of said contacts, said trip structure comprising a trip member and a stabilizing bimetal supported on said trip member, said trip device comprising thermal-and-magnetic trip means, said thermal-and-magnetic trip means being disposed generally below said trip structure, said thermal-and-magnetic trip means comprising a first magnetically permeable part, an armature cooperable with said first magnetically permeable part, said armature in the closed position cooperating with said first magnetically permeable part to generally encompass a first opening, a second magnetically permeable part supported adjacent said first magnetically permeable part-in the lengthwise direction of said housing, a magnetically permeable bimetal support member cooperating with said second magnetically permeable part to encompass a second opening, a conductor connected in electrical series with said contacts and passing lengthwise through said breaker and through said first and second openings, said bimetal support member being adapted to be heated by hysteresis and eddy current losses therein when said conductor is energized, a bimetal member supported on said bimetal support member in a heat conducting relationship with said bimetal support member, said bimetal member when heated a predetermined amount bending to engage said stabilizing bimetal to move said trip structure to effect a thermal tripping operation opening said contacts, said thermal tripping operation occurring with a time delay upon the occurrence of certain overload current conditions below a predetermined value, upon the occurrence of overload curent conditions above said predetermined value said first magnetically permeable part being energized sufficiently to attract said armature whereupon said armature moves to move said trip structure to eifect a magnetic tripping operation opening said contacts without a time delay, said armature comprising a main body portion having a generally planar bottom surface, said bimetal support member comprising a main body portion having a generally planar top surface, the plane of said bottom surface of said main body portion of said armature being higher in said housing than the plane of said top surface of said main body portion of said bimetal support member.

References Cited by the Examiner UNITED STATES PATENTS 2,939,929 6/ 1960 Hobson 20088 3,141,081 7/ 1964 Cellerini 20088 3,205,325 9/1965 Archer et a1 20088 BERNARD A. GI'LHEANY, Primary Examiner.

E. N. ENVALL, ]R., Assistant Examiner. 

1. A CIRCUIT BREAKER HAVING A LENGTH, A WIDTH AND A HEIGHT, SAID CIRCUIT BREAKER COMPRISING A PAIR OF CONTACTS, A TRIP DEVICE COMPRISING A TRIP STRUCTURE OPERABLE TO EFFECT OPENING OF SAID CONTACTS, SAID TRIP DEVICE COMPRISING A FIRST MAGNETICALLY PERMEABLE PART, AN ARMATURE, SAID ARMATURE IN THE CLOSED POSITION COOPERATING WITH SAID FIRST MAGNETICALLY PREMEABLE PART TO GENERALLY ENCOMPASS A FIRST OPENING, A SECOND MAGNETICALLY PERMEABLE PART SUPPORTED ADJACENT SAID FIRST MAGNETICALLY PERMEABLE PART A MAGNETICALLY PERMEABLE BIMETAL SUPPORT MEMBER COOPERATING WITH SAID SECOND MAGNETICALLY PERMEABLE PART TO GENERALLY ENCOMPASS A SECOND OPENING, A CONDUCTOR CONNECTED IN ELECTRICAL SERIES WITH SAID CONTACTS AND PASSING THROUGH SAID FIRST AND SECOND OPENINGS, SAID ARMATURE COMPRISING A MAIN BODY PORTION, SAID MAIN BODY PORTION OF SAID ARMATURE BEING SPACED HEIGHT-WISE FROM SAID BIMETAL SUPPORT MEMBER IN SAID CIRCUIT BREAKER, A BIMETAL MEMBER SUPPORTED ON SAID BIMETAL SUPPORT MEMBER IN A HEAT CONDUCTING RELATIONSHIP WITH SAID BIMETAL SUPPORT MEMBER, SAID BIMETAL SUPPORT MEMBER BEING ADAPTED TO BE HEATED BY HYSTERESIS AND EDDY CURRENT LOSSES THEREIN WHEN SAID CONDUCTOR IS ENERGIZED, SAID HEAT IN SAID BIMETAL SUPPORT MEMBER BEING CONDUCTED TO SAID BIMETAL MEMBER TO HEAT SAID BIMETAL MEMBER, SAID BIMETAL MEMBER WHEN HEATED A PREDETERMINED AMOUNT OPERATING SAID TRIP STRUCTURE TO EFFECT OPENING OF SAID CONTACTS TO THEREBY EFFECT A THERMAL TRIPPING OPERATION, SAID THERMAL TRIPPING OPERATION OCCURRING WITH A TIME DELAY THE OCCURRENCE OF CERTAIN OVERLOAD CURRENT CONDITIONS BELOW A PREDETERMINED VALUE, UPON THE OCCURRENCE OF OVERLOAD CURRENT CONDITIONS ABOVE SAID PREDETERMINED VALUE SAID ARMATURE BEING ATTTACTED TO SAID FIRST MAGNETICALLY PERMEABLE PART WHEREUPON SAID ARMATURE MOVES TO OPERATE SAID TRIP STRUCTURE TO EFFECT OPENING OF SAID CONTACTS WITHOUT A TIME DELAY. 